Siemens M20 Terminal Technical Description page 21

Siemens Information and Communication Products
Hardware interfaces
General Note:
1) Signal levels on the M20T: 5-15V
2) Signal levels on the M20: 2,8 V
3) Crossing out of signal lines is done inside the M20T so that the M20T can be connected to the PC directly using a stan-
dard non-crossover serial cable.
4) Applications directly connecting to the M20 need to cross out the signal paths as shown in the above figure.
Note: If a Pin is not used it can stay unconnected
A
Version 8 dated 15.03.00 21